BRPI0620351A2 - paper collage - Google Patents

Abstract

PAPER COLLAGE. The present invention relates to an aqueous dispersion of cellulose-reactive sizing agent containing an acid anhydride, an anionic polyelectrolyte and an organic compound containing nitrogen which is umamine or its quaternary ammonium having a molecular weight of less than 180 and / or having one or more hydroxyl groups. The invention further relates to a method for preparing an aqueous dispersion of cellulose-reactive sizing agent which comprises dispersing an acid anhydride in an aqueous phase in the presence of an anionic polyelectrolyte and an organic compound containing nitrogen which is an amine or its quaternary ammonium having a molecular weight of less than 180 and / or having one or more hydroxyl groups. The invention also relates to the use of the aqueous dispersion of cellulose-reactive sizing agent as a stock sizing agent or surface sizing agent in the production of paper. The invention also relates to a process for the production of paper which comprises adding the aqueous dispersion of the cellulose-reactive sizing agent to an aqueous cellulosic suspension.

Description

Patent Descriptive Report for "PAPER COLLAGE".

Field of the Invention

The present invention relates to paper sizing and more specifically to aqueous dispersions of cellulose reactive sizing agent and its preparation and use.

Background of the Invention

Cellulose reactive sizing agents such as those based on alkenyl succinic anhydride (ASA) are widely used in papermaking at neutral or slightly alkaline stock pHs to give the paper and cardboard some degree of wetting and penetration resistance. aqueous liquids. Paper sizing based on cellulose reactive sizing agents is generally provided in the form of dispersions containing an aqueous phase and finely divided particles or droplets of sizing agent dispersed therein. Dispersions are generally prepared with the aid of a dispersing system consisting of an anionic compound, eg sodium lignosulfonate, in combination with a high molecular weight amphoteric or cationic polymer, for example a cationic starch polymer , polyamine, polyamidoamine or vinyl addition.

WO 96/17127 describes aqueous dispersions comprising a cellulose reactive sizing agent and colloidal anionic aluminum modified silica particles.

WO 97/31152 describes aqueous dispersions comprising a reactive sizing agent and an anionic microparticle material. The dispersions may also contain no more than 2% (by weight based on reactive sizing agent weight) of surfactant. The surfactant may be nonionic or anionic.

WO 98/33979 A1 describes an aqueous dispersion of cellulose reactive sizing agent and a dispersing system comprising a cationic organic compound and an anionic stabilizer.

Despite the fact that considerable improvements have been achieved in the preparation, properties and performance of aqueous alkenyl succinic anhydride dispersions, there are still some technical problems associated with the use of such dispersions. Generally, succinic alkenyl anhydride dispersions exhibit poor stability, which evidently leads to difficulties in handling the dispersions, for example, in storage and use. A further drawback is that aqueous dispersions cannot be stored for longer periods of time because alkenyl succinic anhydride readily hydrolyzes and thus becomes ineffective as a sizing agent.

Thus, alkenyl succinic anhydride is generally delivered to paper mills as a liquid, which is then dispersed prior to its use as a sizing agent and the dispersion obtained is generally used within 2 hours to avoid stability problems. insufficient and loss of bonding efficiency. The equipment used to prepare the dispersions provides high shear forces to be able to rid the surfaces and produce dispersions having adequate particle bonding. Such equipment is often both complicated and expensive, and due to the high shear forces usually requires a considerable amount of energy.

It is an object of the present invention to provide an aqueous dispersion of cellulose reactive sizing agent which can be readily prepared using low shear forces and low energy consumption. It is a further object of the present invention to provide an aqueous dispersion of cellulose reactive sizing agent showing improved stability and sizing efficiency. Additional goals will follow.

Summary of the Invention

The invention relates to an aqueous dispersion of cellulose reactive sizing agent containing an acid anhydride, an anionic polyelectrolyte and a nitrogen-containing organic compound which is an amine or its quaternary ammonium having a molecular weight of less than 180 and / or having one or more hydroxyl groups. The invention further relates to a method for preparing an aqueous dispersion of cellulose-reactive sizing agent comprising dispersing an acid anhydride in an aqueous phase in the presence of an anionic polyelectrolyte and a nitrogen-containing organic compound. which is an amine or its quaternary ammonium having a molecular weight of less than 180 and / or having one or more hydroxyl groups.

The invention also relates to the use of the aqueous dispersion of cellulose reactive sizing agent as a stock sizing agent or surface sizing agent in papermaking. The invention further relates to a papermaking process comprising the addition of the aqueous dispersion of cellulosic reactive sizing agent to an aqueous cellulosic suspension and the removal of water from the suspension obtained in a grid as well. a papermaking process comprising applying the aqueous dispersion of cellulose-reactive sizing agent to a cellulosic web. Detailed Description of the Invention

In accordance with the present invention, it has been found that improved paper sizing can be achieved using the present aqueous dispersion of cellulose reactive sizing agent. It has also been found that the present dispersions show better stability over conventional dispersions. Further, it has been found that lower shear forces can be used to prepare the present aqueous dispersions compared to when preparing conventional aqueous dispersions of cellulose reactive sizing agent. Thus the present invention makes it possible to use simple, energy-saving and investment equipment by creating low shear forces, such as, for example, static mixers. The present invention then offers substantial economic and technical benefits.

The cellulose reactive sizing agent according to the invention may be selected from any anhydride based sizing agent known in the art. Suitably the sizing agent is a hydrophobic acid anhydride. Suitable hydrophobic acid hydrides may be characterized by the general formula (I) below, where R1 and R2 are independently selected from saturated or unsaturated hydrocarbon groups which suitably contain from 8 to 30 carbon atoms, or R1 and R2 together with the -COC- moiety may form a 5 to 6 membered ring, optionally being further substituted with hydrocarbon groups containing up to 30 carbon atoms.

<formula> formula see original document page 5 </formula>

Examples of suitable acid anhydrides include alkenyl and alkenyl succinic anhydrides, for example octadecyl succinic anhydride, isooctadecyl succinic anhydride, n-hexadecenyl succinic anhydride, dodecenyl succinic anhydride, decenyl succinic anhydride trihydride octenic anhydride, 1-octyl-2-decenyl succinic and 1-hexyl-2-octenyl succinic anhydride. Examples of suitable acid anhydrides further include the compounds described in U.S. Pat. 3,102,064; 3,821,069; 3,968,005; 4,040,900; 4,522,686; and Re. 29,960, which are incorporated herein by reference.

The cellulose reactive sizing agent according to the invention may contain one or more acid anhydrides, for example one or more succinic alkyl and / or alkenyl anhydrides. Generally, the acid anhydride of the present invention is liquid at room temperature.

The dispersion according to the invention contains a dispersant or dispersing system comprising an electronic polyelectrolyte and a nitrogen-containing organic compound. When used in combination, these compounds are effective as a dispersant for the acid anhydride sizing agent although the anionic polyelectrolyte and the nitrogen-containing organic compound may not be effective as a dispersant when used alone. Preferably, the dispersion is anionic, that is, the dispersion, or dispersion system, has a general anionic charge.

The anionic polyelectrolyte according to the invention may be selected from organic and inorganic compounds and may be derived from natural or synthetic sources. Anionic polyelectrolyte has two or more anionic groups which may be of the same or different types. Examples of suitable anionic groups, that is, groups that are anionic or anionized in an aqueous phase, include silanol, aluminosilicate, phosphate, phosphonate, sulfate, sulfonate and sulfonic and carboxylic acid groups as well as their salts, generally ammonium salts or alkali metal (usually sodium). Anionic polyelectrolytes may be water soluble, for example, linear and branched anionic polyelectrolytes, or dispersible in water, for example, cross-linked and / or particulate anionic polyelectrolytes. Preferably, the water dispersible and / or particulate anionic polyelectrolytes are colloidal, that is, in the colloidal particle size range. The colloidal particles suitably have a particle size of from 1 nm to 100 nm, preferably from 2 to 70 nm and more preferably from 2 to 40 nm. Water dispersible and particulate anionic polyelectrolytes may contain aggregate and / or non-aggregate particles.

Examples of suitable organic anionic polyelectrolytes include anionic polysaccharides such as starches, guar gums, celluloses, chitin, chitosans, glycans, galactans, glucans, xanthan gums, mannas and dextrins. Additional examples of suitable organic anionic polyelectrolytes include synthetic anionic polymers such as condensation polymers, for example, melamine-based naphthalene-based polyurethanes and polymers, for example, condensed naphthalene-sulfonate formaldehyde and polymers of melamine-sulfonic acid and polymers. vinyl addition preparations prepared from ethylenically unsaturated monomers including anionic or potentially anionic monomers, for example acrylic acid, methacrylic acid, maleic acid, itaconic acid, crotonic acid, vinyl sulfonic acid, styrene sulfonate and hydroxyalkyl methacrylate and acrylate phosphates, optionally copolymerized with nonionic ethylenically unsaturated monomers, for example acrylamide, alkyl acrylates, styrene and acrylonitrile as well as derivatives of such monomers, vinyl esters and the like.

Examples of additional suitable organic anionic polyelectrolytes include water-soluble branched polymers and water-dispersible cross-linking polymers obtained by polymerizing a monomer mixture comprising one or more ethylenically unsaturated and optionally anionic or potentially anionic monomers. one or more other ethylenically unsaturated monomers in the presence of one or more polyfunctional crosslinking agents. The presence of a polyfunctional crosslinking agent in the monomer mixture makes it possible to prepare branched polymers, slightly crosslinked polymers and highly crosslinked polymers that are dispersible in water. Examples of polyfunctional crosslinking agents include compounds having at least two ethylenically unsaturated bonds, for example, N, N-methylene bis (meth) acrylamide, polyethylene glycol di (meth) acrylate, N-vinyl (meth) acrylamide, divinylbenzene, triallylammonium salts and N-methylallyl (meth) acrylamide; compounds having an ethylenically unsaturated bond and a reactive group, for example glycidyl (meth) acrylate, acrolein and (meth) acrylamide methylol; and compounds having at least two reactive groups, for example, dialdehydes such as glyoxal, diepoxy compounds and epichlorohydrin.

Organic anionic polyelectrolyte generally has a degree of anionic substitution (DAS) from 0.01 to 1.4, suitably from 0.1 to 1.2 and preferably from 0.2 to 1.0. The anionic polyelectrolyte may contain one or more cationic groups as long as it has a general anionic charge. The molecular weight of anionic polyelectrolyte may vary within wide ranges; generally the molecular weight is above 200 and suitably above 500, while the upper limit is generally 10 million and preferably 2 million.

Examples of suitable inorganic anionic polyelectrolytes include anionic silicon materials, for example, anionic silica-based materials prepared from silicic acid and smectite-like clays. Generally, these anionic polyelectrolytes have negative silanol, aluminosilicate or hydroxyl groups. Examples of suitable inorganic anionic polyelectrolytes include polysilicic acid, polysilicates, polyaluminiosilicates, colloidal silica-based particles, for example silica particles, alumina silica (modified with aluminum) and polysilicate microgels, polyaluminyl silicate microgels, precipitated silica gels, smectite clays, for example montmorillonite, bentonite, hectorite, beidelite, nontronite and saponite. Preferred anionic polyelectrolytes include silica based materials, for example, colloidal silica based particles.

The nitrogen-containing organic compound according to the invention is an amine or its quaternary ammonium. Suitable nitrogen-containing organic compounds include primary, secondary and tertiary amines and their quaternary ammoniums. Suitable nitrogen-containing organic compounds further include monoamines, diamines and polyamines and their quaternary ammoniums. Suitable quaternary ammoniums include protonated, alkylated, arylated and alkarylated amines of the above types which may be formed by reaction of the amines with, for example, acids, for example hydrochloric acid, and methyl chloride, sulfate. dimethyl and benzyl chloride. In a preferred embodiment of the invention, the nitrogen-containing organic compound is an amine or its quaternary ammonium having one or more hydroxyl groups. Preferably one or more hydroxyl groups are present in a terminal portion of one or more substituents of the nitrogen-containing compound, that is, a hydroxyl-terminated amine or its quaternary ammonium.

Examples of nitrogen-containing organic compounds include the following amines and their quaternary ammoniums: diethylene triamine, triethylene tetramine, hexamethylene diamine, diethyl amine, dipropyl amine, diisopropylamine, cyclohexylamine, pyrrolidine, guanidine, triethylamine, mine, diethanol amine, 2-methoxyethyl amine, aminoethylethanol amine, alanine and lysine. Additional examples of suitable nitrogen-containing organic compounds include choline hydroxide, tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide. Preferred nitrogen-containing organic compounds include triethanol amine and its quaternary ammoniums.

The molecular weight of the nitrogen-containing organic compound may vary within wide limits. In a preferred embodiment of the invention, the molecular weight of the amine or its quaternary ammonium is less than 180, suitably up to 170 and preferably up to 160. The molecular weight is generally at least 30. As mentioned herein, the molecular weight The molecular weight of a quaternary ammonium amine means the molecular weight of the cationic part of the quaternary ammonium compound, meaning that the anionic part of the quaternary ammonium compound is not included in the molecular weights given above. For nitrogen-containing organic compounds that are selected from amines and their quaternary ammoniums having one or more hydroxyl groups, the molecular weights may be greater, for example, less than 500 and generally less than 300, although the above mentioned molecular weights. are also suitable for such compounds.

In the present aqueous dispersion, or emulsion, the acid anhydride may be present in an amount of from about 0.1 to about 50% by weight, suitably from 0.1 to about 30% by weight. preferably from about 1 to about 20% by weight based on the weight of the aqueous dispersion. Anionic polyelectrolyte is generally present in an amount of up to about 100 wt.%, Usually from 0.1 to 15 wt.%, Suitably from 0.5 to 10 wt. from 1 to 7% by weight based on the weight of the acid anhydride. The nitrogen-containing organic compound may be present in an amount of up to 20 wt.%, Usually from 0.1 to 15 wt.%, Suitably from 0.5 to 10 wt.% And preferably - from 1 to 7% by weight based on the weight of the acid anhydride. In addition to acid anhydride, anionic polyelectrolyte and nitrogen-containing organic compound, additional compounds may optionally be present in the dispersion. Examples of such compounds include mono-, di- and polyanionic and nonionic surfactants and dispersing agents, stabilizers, extenders and preservatives such as, for example, hydrolysed acid anhydrides, for example alkyl and alkenyl acid anhydrides. hydrolyzed as mentioned above, preferably hydrolysed alkenyl succinic anhydrides, for example hydrolysed acid anhydrides in the form of carboxylic acid and / or carboxylic acid ester derivatives, anionic surfactants such as phosphate esters such as phosphate esters ethoxylates, alkyl sulfates, sulfonates and phosphates, alkylaryl sulfates, sulfonates and phosphates, for example sodium ethoxylated phosphate isotridecyl alcohol. If present, the content of such additional compounds in the dispersion may be from 0.1 to 15% by weight, suitably from 1 to 10% by weight and preferably from 2 to 7%. by weight based on the weight of the acid anhydride. Water is also present in the dispersion and may constitute the remainder of the dispersion up to 100% by weight.

The dispersion according to the invention may be produced by forming a mixture containing acid anhydride, anionic polyelectrolyte and nitrogen-containing organic compound as defined above and dispersing the mixture in the presence of water. The dispersion components may be mixed in any order, but preferably the anionic polyelectrolyte and the nitrogen-containing organic compound are mixed and diluted with water to appropriate concentration, and then the acid anhydride is dispersed therein. The mixture may be dispersed using suitable dispersing equipment providing sufficient degree of dispersion, for example a static mixer providing relatively low shear forces. The dispersion obtained contains acid anhydride droplets generally having a droplet size of from 0.1 to 10 μm in diameter.

Aqueous sizing dispersions according to the invention may be conventionally used in papermaking using any types of cellulosic fibers and they may be used both for surface sizing and internal sizing. The term "paper" as used herein is intended to include not only paper, but all types of cellulose and web sheet products including, for example, paper and cardboard. Cellulosic suspension and finished paper may also contain mineral fillers, and generally the content of cellulosic fibers is at least 50% by weight, based on dry cellulosic suspension or finished paper. Examples of conventional type mineral fillers include kaolin, Chinese clay, titanium dioxide, gypsum, talc and natural and synthetic calcium carbonates such as chalk, ground marble and precipitated calcium carbonate. The present invention also relates to a papermaking process wherein the present aqueous sizing dispersion is either added to an aqueous cellulosic suspension or applied to a cellulosic web or web. Suitably the amount of cellulose reactive sizing agent or added to the cellulosic suspension to be drained into a grid to form paper or applied to the surface of a cellulosic sheet or web as a surface glue, usually on the press. sizing is from 0.01 to 1.0 wt% based on the dry cellulosic suspension and optional fillers, preferably from 0.05 to 0.5 wt% where the dosage is mainly - mainly dependent on the quality of the pulp or paper to be glued and the desired level of gluing.

Aqueous sizing dispersions according to the invention are particularly useful in making paper from an aqueous cellulosic suspension having a high conductivity. The conductivity of the suspension that has the water withdrawn from the grid may be within the range of from 0.3 mS / cm to 10 mS / cm. According to the present invention, good results can be achieved when the conductivity is at least 2.0 mS / cm, notably at least 3.5 mS / cm, particularly at least 5.0 mS / cm and still at least 7.5 mS / cm. Conductivity can be measured using standard equipment such as, for example, a WTW LF330 instrument supplied by Christina Berner. The above values are suitably determined by measuring the conductivity of the cellulosic suspension that is fed to or present in the paper machine headbox or, alternatively, by measuring the conductivity of white water obtained by withdrawing water from the suspension. High conductivity levels mean high salt (electrolyte) levels that can be derived from materials used to form the stock, various stock additives, fresh water supplied to the process, etc. Moreover, the salt content is generally higher in processes where white water is extensively recirculated, which can lead to considerable salt accumulation in the water circulating in the process.

Chemical agents conventionally added to the papermaking cellulosic suspension such as retention aids, aluminum compounds, dyes, moisture resistance resins, optical brightening agents, etc. can of course be used in conjunction with present dispersion. Examples of aluminum compounds include alum, aluminates and polyaluminium compounds, for example polyaluminium chloride and sulfates. Examples of suitable retention aids include cationic polymers, anionic inorganic materials in combination with organic polymers, eg bentonite in combination with cationic polymers, silica-based sols in combination with cationic polymers and cationic and anionic polymers. Particularly good bonding can be obtained when using the dispersion of the invention in combination with retention aids comprising cationic polymers. Suitable cationic polymers include cationic starch, acrylate-based and acrylamide-based polymers, polyethyleneimine, polyamines, polyamidoamines and poly (diallyldimethylammonium chloride) and combinations thereof. Preferred retention aids include cationic starch polymers and cationic acrylamide. In a preferred embodiment of the invention, dispersions are used in combination with a retention system comprising at least one cationic polymer and anionic silicon material, for example silica or bentonite based particles. It is possible to premix one or more components of the present dispersion with a retention aid, for example an anionic silicon material, prior to introducing the mixture then obtained in the cellulosic suspension. Thus, the present aqueous sizing dispersion can be prepared shortly before introduction into the cellulosic suspension by bringing acid anhydride and nitrogen-containing organic compound into contact with an anionic polyelectrolyte such as, for example, a silicon material. aqueous, for example, a sol based on silica or bentonite paste.

The invention is further illustrated in the following examples, which, however, are not intended to limit it. Parts and% refer to parts by weight and% by weight, respectively, unless otherwise stated.

Example 1

Aqueous dispersions according to the invention were prepared by dispersing alkenyl succinic anhydride (ASA) based on an olefin moiety comprising isohexadecenyl anhydrous succinic anhydride in the presence of a mixture of anionic polyelectrolyte and amine in a static Hash tube mixer.

Aqueous dispersions used for comparison in this and additional examples were prepared in a similar manner except that no amines, no colloidal silica, high molecular weight amines and / or amines having no hydroxyl groups were used.

The anionic polyelectrolyte used in this example was colloidal silica (Eka NP 590) as an aqueous sol having a SiO2 content of 8.1 wt.% And containing silica particles with a specific surface area of 850 m2 / g which were surface modified with aluminum. The amine used in this example was triethanol amine (TEA) having a molecular weight of 149.

The anionic polyelectrolyte and amine were mixed in the presence of water to form a mixture that was pumped at one end of the tube at a flow rate of 3.17 l / min and concentrated ASA was pumped from the tube side at a flow rate of 0.167. l / min The pressure drop in the mixing unit was 0.34 MPa (3.4 bar). The dispersion obtained had an ASA content of 5% by weight, anionic polyelectrolyte content (in this example SiO2 content) of 5.0% by weight based on ASA, and amine content ranging from 0 to 2.0% by weight based on ASA.

Dispersions 1 to 4 were prepared as shown in Table 1 where the given SiO2 and amine contents are based on ASA.

Table 1

<table> table see original document page 13 </column> </row> <table>

ASA droplet particle size was measured on a Malvern Mastersizer Microplus after diluting the dispersions with water to an ASA content of 0.5 wt%. The results are shown in Table 2. D (v 0.1), D (v0.5) and D (v 0.9) mean that 10, 50 and 90% of the particles, respectively, had a smaller diameter than given size.

Table 2

<table> table see original document page 14 </column> </row> <table>

As can be seen from Table 2, the dispersions according to the present invention, Dispersions No. 2 to 4, resulted in smaller particle sizes over the dispersion used for comparison, Dispersion No. 1.

Bonding efficiency was evaluated by preparing hand sheets according to the standard method SCAN-C26: 76 and bonding was measured as Cobb-60 values according to the standard method Tappi T441.

Paper sheets were prepared according to a process wherein dispersions were added to an aqueous cellulosic suspension comprising recycled pulp having a fiber concentration of 0.5 g / l, conductivity of 0.7 mS / cm and pH around 7 .0. Dispersions were added in amounts of 0.5, 1.0 and 1.5 kg / t, calculated as ASA and based on the weight of dry cellulosic suspension. A retention system was used comprising 6 kg / t cationic potato starch (Perlbond970) and 0.5 kg / t silica sol (Eka NP 442), calculated as dry substances in dry cellulosic suspension.

Cobb-60 values were measured and the results are presented in Table 3. A smaller Cobb value means that a smaller amount of water was absorbed and thus better bonding was achieved. Table 3

<table> table see original document page 15 </column> </row> <table>

As can be seen from Table 3, the dispersions according to the present invention, Dispersions Nos. 2 to 4 resulted in improved bonding efficiency over the dispersion used for comparison, Dispersion No. 1.

Example 2

Dispersions were prepared and the sizing efficiency of the dispersions was evaluated according to the general procedures of Example 1, except that varying silica contents were used and the amine content was constant. The dispersions had an ASA content of 5% by weight based on the weight of the dispersion. Table 4 shows the results.

Table 4

<table> table see original document page 15 </column> </row> <table>

As can be seen from Table 4, the dispersions according to the present invention, Dispersions Nos. 6 through 9 resulted in improved collating efficiency over the dispersion used for comparison, Dispersion No. 5. Example 3

Dispersions were prepared and evaluated according to the general procedures of Example 1. Comparisons of dispersions were made in aqueous cellulosic suspensions having increased conductivity by the addition of calcium chloride. The conductivity of the suspensions was measured using a Christian Berner WTW LF330 instrument. The results are presented in Table 5.

Table 5

<table> table see original document page 16 </column> </row> <table>

As can be seen from Table 5, the dispersion according to the present invention, Dispersion No. 11, showed considerably better sizing efficiency than the dispersion used for comparison, Dispersion No. 910, when the conductivity of the suspension was increased. Example 4

Sprays were prepared and evaluated according to the general procedures of Example 1, except that different amines were used. The dispersion obtained had an ASA content of 5 wt%, SiO2 content of 5.0 wt% based on ASA, and amine content of 2.0 wt% based on ASA.

The amines used were triethanol amine (TEA) having a molecular weight of 149, diethylene triamine (DETA) having a molecular weight of 103, a fractionated coconut grease amine (FCA) having a molecular weight of about 200 and a dimethylammonium chloride tallow (DTD-MAC) having a molecular weight of about 530.

Particle sizes are presented in Table 6. Table 6

<table> table see original document page 17 </column> </row> <table>

Bonding efficiency results are shown in Table 7.

Table 7

<table> table see original document page 17 </column> </row> <table>

As can be seen from Tables 6 and 7, the dispersions according to the present invention, Dispersions Nss. 14 and 15, containing amines having a molecular weight of less than 180 (Dispersions

Nos. 14 and 15) and having hydroxyl groups (Dispersion Ne 15) resulted in smaller particle size and considerably improved bonding efficiency over the dispersions used for comparison, Dispersions Nos. 12 and 13. This also means that less energy was required to clear surfaces in accordance with the present invention.

Example 5

Dispersions were prepared and evaluated according to the general procedures of Example 1, except that different anionic polyelectrolytes were used. The dispersion obtained had an ASA content of 5% by weight, SiO2 content of 5.0% by weight based on ASA and triethanol amine content of 0 or 2.0% by weight based on ASA. The anionic polyelectrolytes used are shown in Table 8. Table 8

<table> table see original document page 18 </column> </row> <table>

The bentonites were slurried (5% by weight of bentonite) and stored for 5 days to achieve sufficient swelling and decamination.

Particle size was determined and stability was assessed. Stability was measured 2 hours after preparation. If still stable after 24 hours, particle size was determined again. The term "sep." means separation. Results are shown in Table 9. Table 9

<table> table see original document page 19 </column> </row> <table> The results of gluing efficiency evaluation are shown in Table 10.

Table 10

<table> table see original document page 20 </column> </row> <table>

As can be seen from Tables 9 and 10, the dispersions according to the present invention, Dispersions Nss. 17, 19, 21, 23 and 25, which contained both anionic polyelectrolyte and nitrogen-containing organic compound, showed better bonding efficiency, better stability and resulted in smaller particle size over the dispersions used for comparison, Dispersions Nes. 16, 18, 20, 22 and 24, which did not contain any nitrogen-containing organic compounds.

Example 6

Dispersions were prepared and particle size and sizing efficiency of dispersions were evaluated according to the general procedures of Example 1, except that different surfactants and varying surfactant contents were used. The anionic polyelectrolyte used was colloidal silica (Eka NP 780) in the form of aqueous sol having a S1O2 content of 7.5% by weight and containing silica particles with a specific surface area of about 900 m2 / g and which were modified. with aluminum. The amine used was triethanol amine (TEA). The dispersion obtained had an ASA content of 5 wt%, SiO2 content of 5.0 wt% based on ASA, and amine content of 2.0 wt% based on ASA.

No surfactant was incorporated into Dispersion No. 26. Hydrolyzed ASA was incorporated as a surfactant into Dispersions No. 1. 27 and 28. The surfactant used in Dispersion No. 29 was phosphate ester (poly (oxy-1,2-ethanediyl) alpha-isotridecyl omega hydroxyphosphate). Surfactant levels in dispersions were based on ASA. The results of particle size measurements are shown in Table 11.

Table 11

<table> table see original document page 21 </column> </row> <table>

Bonding efficiency of the dispersions was evaluated and comparisons of the dispersions were made in an aqueous cellulosic suspension comprising 70% pulp (80/20 birch / pine kraft) and 30% load (CaCO3).

Table 12

<table> table see original document page 21 </column> </row> <table>

As can be seen from the results presented in Tables 11 and 12, Dispersions Nos. 27, 28 and 29 containing a surfactant resulted in smaller particle size and showed better bonding efficiency than dispersion containing no surfactant.

Example 7

The dispersions of Examples 6 were evaluated for sizing efficiency when using aqueous cellulosic suspensions comprising unbleached Kraft pulp having varying conductivities. Results are shown in Table 13.

Table 13

<table> table see original document page 22 </column> </row> <table>

As can be seen from Table 13, Dispersions N9s. 27, 28 and 29 containing a surfactant showed better bonding efficiency than dispersions containing no surfactant, Dispersion Ns 26.

Claims (24)

1. Aqueous dispersion of cellulose reactive sizing agent containing an acid anhydride, an anionic polyelectrolyte and a nitrogen-containing organic compound which is an amine or its quaternary ammonium having a molecular weight of less than 180. 2. Aqueous dispersion of cellulose reactive sizing agent containing an acid anhydride, an anionic polyelectrolyte and a nitrogen-containing organic compound which is an amine or its quaternary ammonium having one or more hydroxyl groups. A method for preparing an aqueous dispersion of cellulose reactive sizing agent comprising dispersing an acid anhydride in an aqueous phase in the presence of an anionic polyelectrolyte and a nitrogen-containing organic compound which is an amine or its amine. quaternary ammonium having a molecular weight of less than 180. A method for preparing an aqueous dispersion of cellulose reactive sizing agent comprising dispersing an acid anhydride in an aqueous phase in the presence of an anionic polyelectrolyte and a nitrogen-containing organic compound which is an amine or its amine. quaternary ammonium having one or more hydroxyl groups. Aqueous dispersion according to any one of claims 1 and 2, or method according to any one of claims 3 or 4, wherein the nitrogen-containing compound has a molecular weight of up to 170. Aqueous dispersion according to any one of claims 1, 2 and 5, or method according to any one of claims -3 to 5, wherein the nitrogen-containing compound has a molecular weight of up to -160. Aqueous dispersion according to any one of claims 1, 2, 5 and 6, or method according to any one of claims 3 to 6, wherein the nitrogen-containing compound has one or more hydroxyl groups. Aqueous dispersion according to claim 7 or a method according to claim 7, wherein one or more hydroxyl groups are present at a terminal position of one or more substituents of the nitrogen-containing compound. Aqueous dispersion according to any one of claims 1, 2 and 5 to 8 or method according to any one of claims 3 to 8, wherein the nitrogen-containing compound is an amine. Aqueous dispersion according to any one of claims 1, 2 and 5 to 8, or method according to any one of claims 3 to 8, wherein the nitrogen-containing compound is a quaternary ammonium. Aqueous dispersion according to any one of claims 1, 2 and 5 to 10 or method according to any one of claims 3 to 10, wherein the nitrogen-containing compound is diethylene triamine, triethylene tetramine, hexamethylene diamine , diethyl amine, dipropyl amine, diisopropyl amine, cyclohexylamine, pyrrolidine, guanidine, triethanol amine, monoethanol amine, diethanol amine, 2-methoxyethyl amine, aminoethanol amine, alanine, lysine, choline hydroxide, tetramethyl ammonium hydroxide or tetraethyl ammonium hydroxide. Aqueous dispersion according to any one of claims 1, 2 and 5 to 11, or method according to any one of claims 3 to 11, wherein the anionic polyelectrolyte is an inorganic material. Aqueous dispersion according to claim 12, or a method according to claim 12, wherein the anionic polyelectrolyte is a silicon material. Aqueous dispersion according to claim 13, or a method according to claim 13, wherein the anionic polyelectrolyte is benzite. Aqueous dispersion according to claim 13, or a method according to claim 13, wherein the anionic polyelectrolyte comprises silica based particles. Aqueous dispersion according to any one of claims 1, 2 and 5 to 15, or a method according to any one of claims 3 to 15, wherein the acid anhydride is isooctadecenyl succinic anhydride, isooctadecyl succinic anhydride, succinic hexadecenyl, succinic dodecenyl anhydride, succinic decenyl anhydride, succinic octenyl anhydride, succinic tri-supervenyl anhydride, 1-octyl-2-decenyl succinic anhydride or 1-hexyl-2-octenyl succinic anhydride. Aqueous dispersion according to any one of claims 1, 2 and 5 to 16, or method according to any one of claims 3 to 16, wherein the acid anhydride is present in an amount of from 0 to 1 to 30% by weight based on the weight of the aqueous dispersion. Aqueous dispersion according to any one of claims 1, 2 and 5 to 17, or method according to any one of claims 3 to 17, wherein the anionic polyelectrolyte is present in an amount of from 0.5 to 10 % by weight based on the weight of the acid anhydride. Aqueous dispersion according to any one of claims 1, 2 and 5 to 18, or method according to any one of claims 3 to 18, wherein the nitrogen-containing organic compound is present in an amount of from 0.5 to 10% by weight based on the weight of the acid anhydride. Aqueous dispersion according to any one of claims 1, 2 and 5 to 19, or method according to any one of claims 3 to 19, wherein the dispersion further comprises an anionic surfactant. An aqueous dispersion according to claim 20, or a method according to claim 20, wherein the anionic surfactant is hydrolyzed acid anhydride. Use of the aqueous dispersion of cellulose reactive sizing agent according to any one of claims 1 to 21 for sizing or surface sizing in papermaking. 23. A papermaking process comprising adding an aqueous dispersion of cellulose-reactive sizing agent to an aqueous cellulosic suspension and removing water from the slurry obtained in a grid, or by applying an aqueous dispersion of sizing agent. cellulose reactive surface of a cellulosic web or web, wherein the dispersion is an aqueous dispersion of cellulose reactive sizing agent according to any one of claims 1 to 21. A process according to claim 22, wherein the aqueous cellulosic suspension has a conductivity of at least 2.0 mS / cm.